Dynamic Search in C # and WPF

Good morning.

I would do the screen only with the "value" and with the "fields" that should be used for the search. Something like the following:

All"fields" selected by the user would be added to a list, and the pesquisarCliente method would look like this:

public List<Cliente> pesquisarCliente(string valor, List<string> campos)
{
    string sql;

    string where = "";
    for (int i = 0; i < campos.Count(); i++)
    {
        where += string.Format("{0} LIKE '%{1}%'", campos[i], valor);
        if (i < campos.Count() - 1)
        {
            where += " OR ";
        }
    }

    sql = string.Format("SELECT * FROM Clients WHERE ({0});", where);

    // Executar sql aqui e retornar lista com clientes encontrados
}

//Metodo Pesquisar elo artigo
public static List<Cliente> Pesquisar_Artigo(string condicao, string campo, string    valor)
{
    string cn = Properties.Settings.Default.SGV;
    SqlConnection conexao = new SqlConnection(cn);
    SqlCommand cmd = new SqlCommand();
    cmd.Connection = conexao;
    cmd.CommandType = CommandType.Text;

    //Faz o teu case aqui
    cmd.CommandText = pesq;

    //Aqui faz o teu parametro
    ex.: cmd.Parameters.AddWithValue("@Cliente", Nome);
    conexao.Open();
    SqlDataReader dr;
    dr = cmd.ExecuteReader();
    List<Cliente> Pesquisa = new List<Cliente>();
    if (dr.Read())
    {
        //Instacia a classe e depoius adciona todos os atributos ex.: 
        Ciente obj = new Cliente();
        obj.id_cliente = Convert.ToInt32(dr["id_cliente"].ToString());
        obj.Nome = dr["Nome"].ToString();

        Pesquisa.Add(obj);
    }
    return Pesquisa;
}    

Uses Entity Framework + npgsql works 100% and you make all kinds of queries you need

PostgreSql + EntityFramework a necessary change (I do not know if it is more after so much time that I use) is to add the OnModelCreating in your Context class which is the default database schema (I think this does not have in the article)

protected override void OnModelCreating(DbModelBuilder modelBuilder)
{
   modelBuilder.HasDefaultSchema("public");
}

Query example:

public List<Pessoa> ListarPaginado(string noDoc, string nome, string email, int currentPage, int pageSize, out int totalPaginas)
    {
        var pagina = (currentPage - 1) >= 0 ? (currentPage - 1) : 0;
        if (pageSize <= 0) pageSize = 1;

        using (var db = new MeuContext())
        {
            var total = db.Pessoas.Count(x =>
                (
                    !string.IsNullOrEmpty(noDoc)
                    ? x.Documentos.Any(d => d.NoDoc.Contains(noDoc))
                    : x.Id > 0
                )
                &&
                (
                    !string.IsNullOrEmpty(email)
                    ? x.Email.Contains(email)
                    : x.Id > 0
                )
                &&
                (
                    !string.IsNullOrEmpty(nome)
                    ? x.Nome.Contains(nome)
                    : x.Id > 0
                )
                && x.Id > 1 //Não mostra o Admin
            );
            totalPaginas = total % pageSize > 0 ? (total / pageSize) + 1 : total / pageSize;

            return db.Pessoas.Where(x =>
                (
                    !string.IsNullOrEmpty(noDoc)
                    ? x.Documentos.Any(d=>d.NoDoc.Contains(noDoc))  
                    : x.Id > 0
                )
                &&
                (
                    !string.IsNullOrEmpty(email)
                    ? x.Email.Contains(email)
                    : x.Id > 0
                )
                &&
                (
                    !string.IsNullOrEmpty(nome)
                    ? x.Nome.Contains(nome)
                    : x.Id > 0
                )
                && x.Id > 1 //Não mostra o Admin
            )
            .Include(x=>x.Documentos)
            //.Include(x=>x.Enderecos)
            .OrderBy(x => x.Nome)
            //.ThenBy(x => x.NoDoc)
            .Skip(pagina * pageSize)
            .Take(pageSize)
            .ToList();
        }
    }